Hydrogen Permeation Behavior of Scratch Formed on Zn Coated Steels in Simulated Atmospheric Corrosion Environment

In this study, the electrochemical hydrogen permeation technique was introduced to investigate the relationship between scratch shape and hydrogen permeation on of Zn coated steel with wet and dry cyclic corrosion. Six kinds of scratches with different aspect ratio (width/length) and area were fabricated by focused pulsed Nd: YAG laser irradiation. Hydrogen permeation currents with each scratches formed on Zn coated steels were investigated. Regardless of scratch shapes, the peaks were recorded in hydrogen permeation currents during wetting and Zn corrosion products were observed around and on the formed scratches. The total hydrogen permeation charges calculated from hydrogen permeation currents depended on aspect ratio and area of scratch. It is suggested that Zn corrosion products easily covered high aspect ratio scratch and prevented hydrogen entry. In detail change of hydrogen permeation currents during wet and dry corrosion tests was also explained based on coverage and composition of Zn corrosion products.